Preparation of tertiary amine borane adducts

ABSTRACT

An improved curing agent for use in coatings, laminates, moldings, castings and adhesives comprising the use of an amine-boron adduct component along with anhydride and epoxy component mixtures. Also provided is an improved process for the preparation of tertiary amine borane curing agents.

This is a divisional application of U.S. Ser. No. 07/387,362 filed Jul.19, 1989, now U.S. Pat. No. 5,034,464, which is a continuation of U.S.Ser. No. 07/253,991, filed Oct. 5, 1988, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to curing agents for epoxy/anhydride resins.There are a wide variety of two component compositions available forfinishing substrates. Generally, the mixing of the components occursbefore application, and addition of a curing agent results in a productwith a relatively short (several hour) shelf life. The present inventionwhich teaches the use of amine-borane adducts as curing agents improvesthe usable time in which the composition can be applied to a substrateat the application stage and offers short cure times and hardersurfaces.

Also provided is an improved process for the preparation of tertiaryamine borane adduct curing agents.

Resins containing the curing agents of the current invention are used incoatings, laminates, moldings, castings and adhesives.

2. Prior Art

Commonly assigned patent application Ser. No. 07/051,867 discloses andclaims a coating composition containing 20-80% by weight of reactivebinder components and 80-20% by weight of an organic carrier; the bindercontains about (a) 50-95% by weight, based on the weight of the binder,of an acrylic polymer having at least two reactive anhydride groupswhich consist of polymerized monomers of an ethylenically unsaturatedanhydride and polymerized monomers selected from the group consisting ofalkyl methacrylate, alkyl acrylate and any mixtures thereof, wherein thealkyl groups have 1-8 carbon atoms and the polymer has a weight averagemolecular weight of about 2,000-50,000; (b) 5-50% by weight, based onthe weight of the binder, of a glycidyl component having at least tworeactive glycidyl groups; and the composition contains about 0.1-5% byweight, based on the weight of the binder, of a catalyst (curing agent);and wherein the primary reaction on curing of the composition occursbetween the anhydride groups of the acrylic polymer and the glycidylgroups of the glycidyl component and wherein the composition upon curingforms a hard, glossy and tack free finish.

The useable time in which the composition can be applied by conventionalmeans such as that in Ser. No. 07/051,867 is about 1 to 6 hoursdepending on the surrounding temperature conditions.

U.S. Pat. No. 3,013,016 describes the synthesis of trialkylamine boraneadducts using sodium or potassium borohydride, an acid such as carbondioxide, the parent amine and a water immiscible solvent. Water is alsopresent during the reaction.

Czech Patent 242,064 also describes a process for the preparation oftertiary amine borane adducts in which a metal borohydride, carbondioxide, a tertiary amine and a solvent are mixed (the borohydride ispresent as a suspension), allowed to react, and then the reactionmixture is washed with water, and the solvent evaporated. Absence ofwater during the reaction step eliminates the potential side reaction ofthe borohydride with water.

SUMMARY OF THE INVENTION

The present invention describes the use of amine-borane adducts ascuring agents for epoxy/anhydride resins. These can be used either aloneor in combination with a borane-free amine curing agent. These improvedcuring agents offer

(i) improvement in the useable time in which the composition can beapplied by conventional means such as spraying.

(ii) fast cure with improved hardness of the finish.

The amine borane adduct curing agents are made by an improved process,wherein a tertiary amine is reacted with an alkali metal borohydride andcarbon dioxide in an organic solvent, wherein the improvement is thatthe reaction and subsequent isolation of the product are done in thesubstantial absence of water.

DETAILS OF THE INVENTION

The present invention describes the use of amine-borane adducts ascuring agents for epoxy/anhydride resins which are used in paints,coatings, laminates, moldings, castings and adhesives. These curingagents improve the useable time in which the composition can be appliedto a substrate by conventional means such as spraying and afterapplication allow for fast cure and improved hardness of the finish.

Typically, the reactive components used for making an epoxy/anhydrideresin are an anhydride bearing polymer or copolymer and an epoxy bearingpolymer or copolymer. The anhydride or epoxy bearing polymers may be ina solvent. These components, along with a catalyst (curing agent) areoften provided to the user in separate containers and are mixed ondemand.

The anhydride component, of the epoxy/anhydride resins which are usefulfor the curing agents of this invention, may be any polymer or copolymerwith a weight average molecular weight of ≦100,000 containing at leasttwo reactive anhydride groups.

Preferred anhydride components are copolymers prepared from one or moreof the monomers of styrene, methacrylates, or acrylates with one or moreof the monomers of itaconic acid, itaconic anhydride, maleic anhydrideor isobutenyl succinic anhydride. After formation of the polymer theitaconic acid which is contained in the polymer is converted to theanhydride.

The epoxy component, of the epoxy/anhydride resins which are useful forthe curing agents of this invention, may be any polymer or copolymerwith a weight average molecular weight of ≦100,000 containing at leasttwo epoxy groups.

Preferred epoxy components are copolymers prepared from methacrylateswith glycidylmethacrylate in combination with the polyglycidylethers ofsorbitol.

The coating composition formed using the components described maycontain 20% to 80% of the polymer or copolymer having at least twoanhydride groups and 80% to 20% of the polymer or copolymer having atleast two epoxy groups.

Neither component should contain any substituents which would interferewith the curing process.

Any amine-borane adduct can be used in the instant invention. Preferredamine-borane adducts are those containing tertiary amines and include1,4-diazabicyclo[2.2.2]octane-monoborane,2-methyl-1,4-diazabicyclo[2.2.2]octane-monoborane, alkyl substituted1,4-diazabicyclo[2.2.2]octane-monoborane wherein the alkyl groupscontain up to about 6 carbon atoms,N,N,N',N'-tetramethylethylenediaminemonoborane,N,N-dimethyl-1,3-propanediaminemonoborane, N,N-dimethyl ethanolamine-borane, N,N-diethyl ethanol amine-borane, N,N-dibutyl ethanolamine-borane, N,N-diethyl hexanol amine-borane.

Especially preferred adducts are1,4-diazabicyclo[2.2.2]octane-monoborane and alkyl substituted1,4-diazabicyclo[2.2.2]octane-monoborane wherein the alkyl groupscontain up to about 6 carbon atoms. The most Preferred adducts are1,4-diazabicyclo[2.2.2]octane-monoborane and2-methyl-1,4-diazabicyclo[2.2.2]octane-monoborane and/or mixturesthereof.

The amine-borane adducts of this invention can be made by directinteraction of the amines with borane-dimethylsulfide complex orborane-THF complex or by the procedures disclosed by VanPaasschen etal., Canadian Journal of Chemistry, 53, 723-726 (1975); Gatti et al.,Inorganic Chemistry, 5, 2075-2076 (1966) or Brown, et al., InorganicChemistry, 19, 455-457 (1980) or, preferably, by the method describedbelow.

In using amines which contain more than one nitrogen in the molecule, itis to be understood that one, several, or all of the nitrogens may becomplexed with borane.

The concentration of amine-borane adducts contained in theepoxy/anhydride composition can range from 1 to 6% by weight.

The amine-borane adducts can be used as the sole catalyst or blendedwith borane-free amines.

Use of the amine-borane adducts in place of the parent amines as curingagents for epoxy/anhydride resins increases the useable time in whichthe composition can be applied by conventional means and, afterapplication, still offers short cure times and improved hardness of thefinish.

Tertiary amine borane adducts are made by an improved process, byreacting an alkali metal borohydride, carbon dioxide, and a tertiaryamine in an organic solvent, the improvement being the substantialabsence of water during the reaction and the isolation of the amineborane adduct. The improved process gives very high yields of thetertiary amine borane adduct, and the product is often purer than fromprior art processes. In addition, fewer steps are required in theimproved process, giving it an economic advantage over prior artprocesses.

Preferred alkali metal borohydrides are lithium borohydride, sodiumborohydride and potassium borohydride. Any organic solvent thatdissolves the amine and amine borane adduct is satisfactory, provided itdoes not react with any of the reactants or products. It is preferredthat the solvent does not dissolve the inorganic by-product. A lowboiling point solvent is desirable so it can be easily removed duringthe isolation step. Suitable solvents include hydrocarbons such astoluene, halogenated hydrocarbons such as carbon tetrachloride andnitriles such as acetonitrile and benzonitrile. Nitriles are preferredsolvents, and acetonitrile is especially preferred. Solvents that formvery stable adducts with borane are not suitable.

By substantial absence of water is meant that the starting materials aredry, that is contain less than about 1.0% water and preferably less than0.1% water and most preferably less than 0.05% water, and that thereaction and isolation are done under conditions under which substantialamounts of water cannot enter the reaction (as from the atmosphere) suchthat the above low water levels are maintained throughout the reactionand isolation of the amine borane adduct. It is therefore preferred tocarry out the process under an inert gas such as nitrogen or argon tothe greatest extent practicable. Short exposures to the atmosphere arenot harmful.

To carry out the process, the tertiary amine, alkali metal borohydrideand solvent are added to the reaction vessel and stirred. Theproportions of alkali metal borohydride to tertiary amine are usuallyabout 1:1 on a molar basis (substantially different ratios can be used,but result in a waste of materials) if a monoborane adduct is desired.Monoborane adducts are preferred, but bisborane adducts of diamines canalso be made. The proportion of solvent used is not critical, but enoughshould be used so that a smooth easily stirred slurry is formed (theinorganic borohydrides and by-product salts are substantially insolublein the organic solvent). The mixture is then stirred (vigorous stirringis desirable) while carbon dioxide is added as by bubbling into theliquid or passing over the surface of the liquid for, typically, 1 to 5hours until the reaction is complete (uptake of carbon dioxide ceases).The temperature during this time is about -10° C. to the boiling pointof the solvent or tertiary amine, whichever boiling point is lower,providing of course that the reactants and products are stable at theboiling point of the solvent or tertiary amine. A preferred range isambient temperature to about 50° C. The product is then isolated byfiltering off the inorganic by-product, and removing the solvent as bydistillation or evaporation. Further illustration of the process will befound in the Examples.

Although any tertiary amine borane adduct may be made by the abovemethod (assuming the monoborane adduct of the amine is stable), it isespecially useful for preparing the monoborane adducts of1,4-diazabicyclo[2.2.2]octane and alkyl substituted1,4-diazabicyclo[2.2.2]octanes wherein the alkyl groups contain up toabout 6 carbon atoms. It is most useful for preparing the monoboraneadducts of 1,4-diazabicyclo[2.2.2]octane and2-methyl-1,4-diazabicyclo[2.2.2]octane.

EXPERIMENT 1 Preparation of 1,4-Bicyclo[2.2.2]octane-Monoborane Use of(CH₃)₂ S:BH₃ Complex

In the hood, a 0.5 1 3-neck round bottom flask was charged with 19.1 g(0.17 mol) 1,4-diazabicyclo[2.2.2]octane and a stirbar. The1,4-diazabicyclo[2.2.2]octane was dissolved in approximately 250 ml oftoluene. A nitrogen purge was started through the solution via a gasdispersion tube. The nitrogen was exited through a dry ice trap. To the1,4-diazabicyclo[2.2.2]octane solution was added, via syringe, 10.0 mlof refrigerated 10M borane-dimethyl sulfide complex. A crystalline solidbegan forming just after the addition was complete. While stirring, thesolution was heated to drive off any remaining dimethyl sulfide. Thesolution was cooled to room temperature, allowing more solid torecrystallize, then filtered through a fritted glass funnel under anitrogen blanket. A ¹ H NMR spectrum of the first crop (8.00 g, mp164°-165° C.) showed it to be 1,4diazabicyclo[2.2.2]octane-monoborane. Asecond crop of product (4.48 g, mp 164°-165° C.) was collected. Totalyield was 12.48 g (99%).

EXPERIMENT 2 Preparation of 1,4-Diazabicyclo[2.2.2]octane-Monoborane Useof C₄ H₈ O:BH₃ Complex

In the hood, a 2 1 round bottom flask was charged with 89.6 g (0.8 mol)1,4-diazabicyclo[2.2.2]octane and a stirbar. A minimal amount of dry THF[C₄ H₈ O] was added to stir the 1,4-diazabicyclo[2.2.2]octane and theflask was capped with a supa seal septa. The slurry was kept cool via anice bath. To the cold slurry was added, via cannula over approximately45 minutes, 800 ml of 1M borane-THF complex. The mixture was warmed toroom temperature and stirred for 3 hours. The solution was then takeninto the drybox and filtered through a fritted funnel. [A 150 ml orlarger funnel was required to contain the filtered solids]. Additionalsolvent was removed from the filtrate by evaporation and a second cropof crystals was collected by filtration. First crop yield was 34.03 g,mp 159°-162° C., second crop yield was 33.95 g, mp 160°-163° C. ¹ HNMR's of both solids shows them to be the desired1,4-diazabicyclo[2.2.2]octane-monoborane.

EXAMPLE 1 Resin Preparation #1 [Anhydride Component]

The following ingredients were charged to a reactor equipped with athermometer, stirrer, dropping funnel, water separator, nitrogen purgeand condenser.

    ______________________________________                                        Portion 1                                                                     Xylene                  232.10 g                                              Portion 2                                                                     Styrene                 91.70 g                                               Butylmethacrylate       122.20 g                                              Butylacrylate           232.2  g                                              Xylene                  50.20 g                                               Portion 3                                                                     Itaconic acid           191.60 g                                              Xylene                  60.00 g                                               Portion 4                                                                     75% Tert-butylperoxyacetate                                                                           30.50 g                                               Propyleneglycolmonomethyletheracetate                                                                 12.10 g                                               Xylene                  57.50 g                                               Portion 5                                                                     Propyleneglycolmonomethyletheracetate                                                                 102.10 g                                              Portion 6                                                                     Propyleneglycolmonomethyletheracetate                                                                 102.10 g                                              ______________________________________                                    

Portion 1 was added to the reactor and heated to reflux. Portion 2 waspremixed and fed to the reactor over three hours simultaneous withportion 3. Portion 3 was predispersed to form a pumpable slurry and fedto the reactor over three hours simultaneous with portion 2. Portion 4was premixed and fed to the reactor over 3 hours and 20 minutes startingwith the start of portion 2. The batch was maintained at reflux until25.2 g of water was collected in the water separator. Portion 5 was thenadded to the batch and 341.3 g of solvent removed by distillation.Portion 6 was then added to the reaction mixture.

Resin Preparation #2 [Epoxy Component]

The following ingredients were charged to a reactor equipped with athermometer, stirrer, dropping funnel, nitrogen purge and condenser.

    ______________________________________                                        Portion 1                                                                     Butylacetate              148.93  g                                           Toluene                   25.51   g                                           Ethylacetate              41.39   g                                           Portion 2                                                                     Glycidylmethacrylate      233.12  g                                           Butylacetate              6.25    g                                           Butylmethacrylate         155.41  g                                           Portion 3                                                                     Vazo 67 initiator from Du Pont                                                                          18.68   g                                           Butylacetate              56.03   g                                           Portion 4                                                                     Vazo 67 initiator from Du Pont                                                                          4.77    g                                           Butylacetate              14.32   g                                           Portion 5                                                                     Butylacetate              95.75   g                                           Propyleneglycolmonomethyletheracetate                                                                   48.32   g                                           ______________________________________                                    

Portion 1 was added to the reactor and heated to reflux. Portion 2 waspremixed and added to the reactor over 2 hours simultaneous with portion3. Portion 3 was premixed and added to the reactor over two hourssimultaneous with portion 2. Portion 4 was added to the reactor over 30minutes after the completion of portion 2 and 3. The reaction was heldat reflux for 30 minutes. Portion 5 was added to the mixture and blendedin.

Coating Compositions

The following compositions were made by thoroughly blending thefollowing ingredients:

    ______________________________________                                        Ingredients    A             B         C                                      ______________________________________                                        Resin #1       23.2   g      22.95                                                                              g    23.26                                                                              g                                 Resin #2       12.86  g      12.72                                                                              g    12.89                                                                              g                                 Araldite GY-358                                                                              2.44   g      2.41 g    2.45 g                                 (Sorbitol Polyglycidyl-                                                       ether from Ciba-Geigy)                                                        1,4-Diazabicyclo[2.2.2]-                                                                     0      g      0    g    0.49 g                                 octane                                                                        1,4-Diazabicyclo[2.2.2]-                                                                     0.54   g      0.81 g    0    g                                 octane-monoborane                                                             Butylacetate   10.93  g      11.09                                                                              g    10.90                                                                              g                                 ______________________________________                                    

These coating compositions were applied to a glass substrate by drawdowns with a 0.010 inch blade and allowed to cure at room temperature.Gel times were run in a Gardner-Holdt tube. Hardness was determined witha persoz hardness pendulum.

The results are given below:

    ______________________________________                                        Modification A           B        C                                           ______________________________________                                        Gel Time     23 hours    15 hours 5 hours                                     Persoz Hardness                                                                            110         121      100                                         (7 Day)                                                                       Film Thickness                                                                              72          69       70                                         (microns)                                                                     ______________________________________                                    

The results clearly show that the useable time in which the compositioncan be applied by conventional means as measured by the gel time for thecoating mixture containing 1,4-diazabicyclo[2.2.2]octane-monoborane asthe curing agent is 3 to 4.6 times that of the coating mixturecontaining 1,4-diazabicyclo[2.2.2]octane as the curing agent. Also thecoating mixture containing the 1,4-diazabicyclo[2.2.2]octane-monoboraneas the curing agent has resulted in the formation of a finish with aharder surface.

EXAMPLE 2 Preparation of Hydroxyl Functional Polymer A

The following ingredients were charged to a reactor equipped with athermometer, stirrer, dropping funnel, water separator, nitrogen purgeand condenser.

    ______________________________________                                        Portion 1                                                                     Methyl amyl ketone (MAK)                                                                              384.064 g                                             Portion 2                                                                     Methyl methacrylate     94.970  g                                             Hydroxy ethyl acrylate  189.940 g                                             Styrene                 94.970  g                                             Butyl acrylate          253.230 g                                             Portion 3                                                                     Methyl amyl ketone      45.200  g                                             Butyl peracetate        21.080  g                                             ______________________________________                                    

Portion 1 was charged to the reactor, covered with nitrogen and heatedto reflux temperature. Portions 2 and 3 were then fed simultaneouslyupon reaching reflux. Portion 2 is fed at a rate of 2.82 g/min. overa225 min. period, and portion 3 is fed at 0.264 g/min. over 240 mins. Thereaction is then held at reflux for 30 mins. at the conclusion ofportion 3. At the end of the 30 min., 218.454 g of MAK are recovered tobring the resulting polymer to 75% solids and a Gardner-Holdt viscosityof Z-Z2.

    ______________________________________                                        Preparation of Glycidyl Functional                                            Acrylic Polymer B                                                             ______________________________________                                        Portion 1                                                                     Glycidyl methacrylate 8.560   g                                               Butyl acrylate        16.370  g                                               Methyl methacrylate   10.740  g                                               Xylene                120.536 g                                               Portion 2                                                                     Glycidyl methacrylate 169.950 g                                               Butyl acrylate        136.610 g                                               Methyl methacrylate   167.770 g                                               Xylene                14.484  g                                               Portion 3                                                                     Xylene                83.450  g                                               Butyl peracetate      22.530  g                                               ______________________________________                                    

Portion 1 was charged to the reactor, covered with nitrogen and heatedto reflux temperature. Portions 2 and 3 were individually premixed andcharged simultaneously over a 300 min. period. Upon completion of thefeed, the reaction mixture is held at reflux for 45 mins.

The resulting polymer had a weight solids content of 69.0-71.0% at aZ-Z2 Gardner-Holdt viscosity. The polymer had a weight average molecularweight of 5,000-7,000.

Preparation of White Dispersion

    ______________________________________                                        Portion 1                                                                     Hydroxyl functional polymer A                                                                         5.500   g                                             Methyl amyl ketone      14.260  g                                             Portion 2                                                                     TiO.sub.2 White pigment 70.000  g                                             Portion 3                                                                     Hydroxyl functional polymer A                                                                         7.840   g                                             Methyl amyl ketone      2.400   g                                             ______________________________________                                    

Portion 1 was added to the blend tank while mixing at low speed and thenmixed for 10 minutes. Portion 2 was added to the blend tank while mixingat low speed and then mixed for 20 minutes at high speed. Portion 3 wasadded to the tank at low speed and then mixed at high speed after thelast addition. The resulting blend was then put through a sand mill forfineness.

Preparation of Coating Composition

A coating composition was prepared by thoroughly blending together thefollowing components:

    ______________________________________                                        Portion 1                                                                     White Dispersion          301.17  g                                           Denecol EX-622 (Nagase) Epoxy Ether                                                                     43.68   g                                           Araldite CY-184 (Ciba-Geigy) Epoxy Ether                                                                48.56   g                                           Glycidyl Functional Acrylic Polymer B                                                                   32.03   g                                           Silicone SF-69 (General Electric)                                                                       0.18    g                                           Portion 2                                                                     Resin Preparation #1 (Anhydride                                                                         353.60  g                                           Component) [From Example 1]                                                   ______________________________________                                    

Preparation of Curing Agent Solutions

    ______________________________________                                                  Standard                                                                             Control   A        B                                         ______________________________________                                        Ethanol     73.81 g  73.81 g   55.86 g                                                                              46.25 g                                 n-Butanol    7.64 g   7.54 g   --     --                                      Butyl Carbitol                                                                            46.93 g  46.93 g   46.95 g                                                                              30.99 g                                 1,4-Diazabi-                                                                              11.92 g   5.96 g    5.96 g                                                                               5.96 g                                 cyclo[2.2.2]-                                                                 octane                                                                        N,N-Dimethyl-                                                                             --        5.96 g    2.98 g                                                                              --                                      ethanol amine                                                                 1,4-Diazabi-                                                                              --       --        29.80 g                                                                              59.60 g                                 cyclo[2.2.2]-                                                                 octane mono-                                                                  borane (10% solids                                                            in Acetone)                                                                   ______________________________________                                    

When the coating composition was mixed with either of the above curingagent solutions the following results were obtained which shows anincrease in catalytic activity using the1,4-diazabicyclo[2.2.2]octane-monoborane adduct, without adverselyaffecting the useable time in which the composition can be applied.

    ______________________________________                                        Properties  Standard Control   A      B                                       ______________________________________                                        Stormer Viscosity                                                                         2 hrs.   5 hrs.    4 hrs. 5 hrs.                                  at 75 KU (Krebs                                                               Units)                                                                        Tack-Free time at                                                                         5 hrs.   9 hrs.    7 hrs. 5 hrs.                                  45 micron dry film                                                            thickness                                                                     ______________________________________                                    

EXAMPLE 3 Resin #1, the Anhydride Component was prepared as inExample 1. The anhydride equivalent weight was 518 gm. per equivalent,based on 100% solids.

    ______________________________________                                        Portion 1                                                                     Butylacetate              244.67  g                                           Toluene                   25.51   g                                           Ethylacetate              41.39   g                                           Portion 2                                                                     Glycidylmethacrylate      233.12  g                                           Butylacetate              62.29   g                                           Butylmethacrylate         155.41  g                                           "Vazo" 67 initiator (from Du Pont)                                                                      18.68   g                                           Portion 3                                                                     Butylacetate              14.32   g                                           Propyleneglycolmonomethyletheracetate                                                                   48.32   g                                           ______________________________________                                    

Portion 1 was added to a reactor equipped with a stirred, thermometer,condenser, nitrogen purge and feed funnel, and heated to reflux. Portion2 was premixed and added to the reactor over 2 hr. while maintainingreflux. Portion 3 was premixed and added over 30 min. after portion 2was added. The batch was held at reflux for 30 additional min., thencooled and filled out. The epoxy equivalent weight was 236.7 g perequivalent, based on 100% solids.

Resin #3 Preparation (Polyol Component)

    ______________________________________                                        Portion 1                                                                     Methyl n-amyl ketone    170.85  g                                             Portion 2                                                                     Methyl n-amyl ketone    61.90   g                                             75% t-Butylperacetate initiator                                                                       27.74   g                                             Portion 3                                                                     Styrene                 143.88  g                                             Ethylmethacrylate       143.88  g                                             Laurylmethacrylate      115.12  g                                             Hydroxyethylacrylate    172.63  g                                             ______________________________________                                    

Portion 1 was added to a reactor equipped with a stirrer, thermometer,condenser, nitrogen purge and two feed funnels, and heated to reflux.Portion 2 was premixed and added to the reactor over 165 min. Portion 3was premixed and added to the reactor over 150 min., starting at thesame time as portion 2. The batch was held at reflux an additional 2hr., then cooled and filled out. The hydroxy equivalent weight based on100% solids was 386.6 g per equivalent.

Coating Compositions

The following coating compositions were made by thoroughly blending thefollowing ingredients (all in grams):

    ______________________________________                                        Ingredients            A       B                                              ______________________________________                                        Resin # 3              13.5    13.5                                           2-Methyl-1,4-diazabicyclo-                                                                            1.315   2.623                                         [2.2.2]octane monoborane                                                      "Tinuvin" 144 (a)      6.3     6.3                                            "Tinuvin" 328 (b)      2.1     2.1                                            Propyleneglycolmonomethyl ether                                                                      4.1     4.1                                            Reducer (c)            12.72   12.23                                          Resin # 1              20.76   20.76                                          Resin # 2               9.78    9.78                                          Denecol EX622 Epoxy Resin (d)                                                                         3.15    3.15                                          ______________________________________                                        (a) From Ciba-Geigy Corp., as a 10% solution in                                   xylene.                                                                   (b) From Ciba-Geigy Corp., as a 30% solution in                                   xylene.                                                                   (c) Reducer is:                                                                   Butyl acetate             19.8                                                Propyleneglycolmonomethyl ether acetate                                                                 13.2                                                Xylene                    23.1                                                n-Hexyl acetate           43.9                                            (d) From Nagase Co.                                                       

Films of the above compositions were cast using a 0.010 inch draw downblade onto panels made of glass and thermoplastic polyolefin. The filmshad the following properties after curing at 25° C.

    ______________________________________                                        Modification          A      B                                                ______________________________________                                        Gel Time (hr)          37     26                                              Persoz Hardness (after 7 days)                                                                      147    152                                              ______________________________________                                    

The results clearly shown the long gel times obtained when themonoborane of 2-methyl-1,4-diazabicyclo[2.2.2]octane is used as thecuring agent.

EXAMPLE 4 Preparation of 1,4-Diazabicyclo[2 2 2]octane-Monoborane

Under dry nitrogen in a 3-neck, 5 L round bottom flask is charged with336.6 grams (3 mol) 1,4-diazabicyclo[2.2.2]octane and 4 L dryacetonitrile. Sodium borohydride (113.5 grams, 3 mol) is added to theacetonitrile solution in a single portion. By means of a mechanicalstirrer the suspension is stirred vigorously. Dry carbon dioxide gas isintroduced over the surface of the solution. The temperature of theacetonitrile suspension is maintained at 40°-50° C. by means of a watercooling bath. The carbon dioxide addition is continued as long as thereis uptake of the gas by the suspension. When the uptake of gas ceasesthe reaction is complete and 100 g of a dry filter aid (e.g. Celite™) isadded to the suspension as a single portion. The warm (40° C.)suspension is filtered under dry nitrogen pressure through a mat offilter aid. The filtrate is evaporated under reduced pressure to yield360.2 g (95.3%) of the desired product as a free flowing powder. Asample of the borane adduct was recrystallized from hot toluene to yielda colorless crystalline solid, mp 162°-164° C. ¹ H NMR (CD₂ Cl₂) δ 1.40(q, 3H, BH₃), 2.86-2.95 (m, NCH₂); ¹³ C NMR (CD₃ CN) δ 46.84, 52.58(CH₂). The mixed filter aid and sodium formate by-product is discarded.

EXAMPLE 5 Preparation of2-methyl-1,4-Diazabicyclo[2.2.2]octane-Monoborane

Under dry nitrogen a 3-neck, 5 L round bottom flask is charged with378.7 grams (3 mol) 2-methyl-1,4-diazabicyclo[2.2.2]octane and 4 L dryacetonitrile. Sodium borohydride (113.5 grams, 3 mol) is added to theacetonitrile solution in a single portion. By means of a mechanicalstirrer the suspension is stirred vigorously. Dry carbon dioxide gas isintroduced by bubbling under the surface of the solution. Thetemperature of the acetonitrile suspension is maintained at 40°-50° C.by means of a water cooling bath. The carbon dioxide addition iscontinued as long as there is uptake of the gas by the suspension. Whenthe uptake of gas ceases the reaction is complete and 100 g of a dryfilter aid (e.g. Celite™) is added to the suspension as a singleportion. The warm (40° C.) suspension is filtered under dry nitrogenpressure through a mat of filter aid. The filtrate is evaporated underreduced pressure to yield 375.0 g (90%) of the desired product as a freeflowing powder. A sample of the borane adduct was recrystallized fromethyl acetate to yield a colorless crystalline solid, mp 78°-80° C. ¹ HNMR (CD₂ Cl₂) δ 1.15 (d, 3H, CH₃), 1.39 (q, 3H, BH₃), 2.33 (m, 1H, C₃CH), 2.75 (m), 2.99 (m); ¹³ C NMR[¹ H] (CH₃ CN) δ, 18.6 (CH₃), 40.2,48.7, 50.5 (C₃ CH), 51.4, 52.7, 59.8. The filter aid and sodium formateby-product is discarded.

COMPARATIVE EXAMPLE 1 Preparation of1,4-Diazabicyclo[2.2.2]-octane-Monoborane

Under dry nitrogen a 4-neck, 500 mL round bottom flask is charged withsodium borohydride (18.9 g, 0.5 mol) and 250 mL ethyl acetate.1,4-Diazabicyclo[2.2.2]octane (56.09 g, 0.5 mol) is added to the ethylacetate solution in a single portion. By means of a mechanical stirrerthe suspension is stirred vigorously. Dry carbon dioxide gas isintroduced into the mixture by bubbling below the surface of thesolution (simply passing the CO₂ gas over the vigorously stirredsuspension also allows a rapid uptake of CO₂). The temperature of theethyl acetate suspension is maintained at 20°-40° C. by means of a watercooling bath. The carbon dioxide addition is continued as long as thereis uptake of the gas by the suspension. When the uptake of gas ceasesthe reaction is complete (4 hr.) and 250 mL deionized water is added tothe suspension in a single portion. The water/ethyl acetate mixture isstirred for 5 minutes to insure complete mixing. By means of aseparatory funnel, the water is separated from the ethyl acetatesolution. The ethyl acetate solution is washed with 100 mL of 20% (byweight) K₂ CO₃ and dried over anhydrous K₂ CO₃. The ethyl acetatesolution is then filtered through glass wool, to remove the K₂ CO₃, andevaporated under reduced pressure to yield 19.24 g (31%) of the desiredproduct as a free flowing powder of good purity, mp 162°-164° C. The ¹ HNMR shows a spectrum consistent with the desired monoborane.

COMPARATIVE EXAMPLE 2 Preparation of2-Methyl-1,4-diazabicyclo[2.2.2]octane-Monoborane

Under dry nitrogen a 4-neck, 500 mL round bottom flask is charged withsodium borohydride (18.9 g, 0.5 mol) and 250 mL ethyl acetate.2-Methyl-1,4-diazabicyclo[2.2.2]octane (63.12 g, 0.5 mol) is added tothe ethyl acetate solution in a single portion. By means of a mechanicalstirrer the suspension is stirred vigorously. Dry carbon dioxide gas isintroduced under the surface of the solution. The temperature of theethyl acetate suspension is maintained at 20°-35° C. by means of a watercooling bath. The carbon dioxide addition is continued as long as thereis uptake of the gas by the suspension. When the uptake of gas ceases (2hr.) the reaction is complete and 100 mL of deionized water is added tothe suspension as a single portion. The water/ethyl acetate mixture isstirred vigorously to insure complete mixing. The water is removed bymeans of a separatory funnel. The ethyl acetate solution is then washedwith 100 mL of 20% (by weight) K₂ CO₃ and dried over anhydrous K₂ CO₃.The ethyl acetate solution is filtered through glass wool, to remove theK₂ CO₃, and evaporated under reduced pressure to yield 55.7 g (79.5%) ofimpure (by ¹ H NMR analysis) borane as a sticky white solid. The impureborane is recrystallized from toluene but some impurities remain so theimpure product is further recrystallized from ethyl acetate to give37.41 g (53%) of pure colorless crystalline product, melting point77°-80° C.

Although preferred embodiments of the invention have been describedhereinabove, it is to be understood that there is no intent to limit theinvention to the precise embodiments described and that variations canbe made without departing from the spirit and scope of the invention asclaimed.

What is claimed is:
 1. A process for the production of tertiary amineborane adducts which comprises reacting an alkali metal borohydride withcarbon dioxide and a tertiary amine in the presence of an organicsolvent chosen so that it does not react with reactants or productsfollowed by isolating of the tertiary amine borane adduct, said reactingand isolating performed in the substantial absence of water, where thewater content is below about 1% water so that the above low levels ofwater are maintained throughout the reaction and isolation of thetertiary amine borane adduct.
 2. The process of claim 1 wherein thealkali metal borohydride is selected from lithium borohydride, sodiumborohydride and potassium borohydride.
 3. The process of claim 1 whereinthe solvent does not dissolve any inorganic by-product of the reaction.4. The process of claim 1 wherein the boiling point of the solvent isbetween about 25° C. and about 125° C.
 5. The process of claim 1 whereinthe solvent is selected from hydrocarbons, halogenated hydrocarbons andnitriles.
 6. The process of claim 5 wherein the hydrocarbon solvent istoluene.
 7. The process of claim 5 wherein the halogenated hydrocarbonsolvent is carbon tetrachloride.
 8. The process of claim 5 wherein thesolvent is a nitrile.
 9. The process of claim 8 wherein the solvent isacetonitrile.
 10. The process of claim 1 where the percent of water isless than 0.1%.
 11. The process of claim 10 wherein the percent of wateris less than 0.05%.
 12. The process of claim 1 wherein the reacting andisolating are carried out under an inert gas.
 13. The process of claim12 wherein the inert gas is selected from nitrogen and argon.
 14. Theprocess of claim 1 wherein the Product is a monoborane and theproportions of alkali metal borohydride to tertiary amine are about 1:1on a molar basis.
 15. The process of claim 1 wherein the reactionmixture is stirred while carbon dioxide is added.
 16. The process ofclaim 1 wherein the temperature during the reacting of said alkali metalborohydride with said carbon dioxide and said tertiary amine is -10° C.to the boiling point of the solvent or tertiary amine, whichever islower.
 17. The process of claim 16 wherein the reaction is conducted atambient temperature to about 50° C.
 18. The process of claim 1 whereinthe isolating of the tertiary amine borane adducts is done by filteringoff any inorganic by-products and removing the solvent by distillationor evaporation.
 19. The process of claim 1 wherein the tertiary amine isselected from 1,4-diazabicyclo[2.2.2]octane and alkyl substituted1,4-diazabicyclo[2.2.2]octane, wherein the alkyl groups have up to 6carbon atoms, and mixtures thereof.
 20. The process of claim 19 whereinthe tertiary amine is selected from 1,4-diazabicyclo[2.2.2]octane and2-methyl-1,4-diazabicyclo[2.2.2]octane and mixtures thereof.
 21. Theprocess of claim 9 wherein the tertiary amine is selected from1,4-diazabicyclo[2.2.2]octane, and2-methyl-1,4-diazabicyclo[2.2.2]octane and mixtures thereof.
 22. Theprocess of claim 17 wherein the solvent is acetonitrile.
 23. The processof claim 22 wherein the tertiary amine is selected from1,4-diazabicyclo[2.2.2]octane, and2-methyl-1,4-diazabicyclo[2.2.2]octane and mixtures thereof.
 24. Theprocess of claim 22 wherein the alkali metal borohydride is selectedfrom sodium borohydride, lithium borohydride, and potassium borohydrideand mixtures thereof.
 25. The process of claim 24 wherein the tertiaryamine is selected from 1,4-diazabicyclo[2.2.2]octane, and2-methyl-1,4-diazabicyclo[2.2.2]octane and mixtures thereof.
 26. Theprocess of claim 16 wherein the alkali metal borohydride is selectedfrom lithium borohydride, sodium borohydride, and potassium borohydrideand/or mixtures thereof, the solvent is acetonitrile, and the tertiaryamine is selected from 1,4-diazabicyclo[2.2.2]octane, and2-methyl-1,4diazabicyclo[2.2.2]octane and mixtures thereof.
 27. Thecompound 2-methyl-1,4-diazabicyclo[2.2.2]octane-monoborane.